SATlife2.net, I do not understand simple maths....

[FrostedxB]

I signed up for the SAT's today and started studying a bit, particularly in the mathematics section (did piss poor the first time I ever took the SAT's) and I just don't seem to understand/remember much.

For instance -
If n is a positive 2-digit integer and both digits of n are the same, how many different values are possible for n?

A - 9
B - 10
C - 12
D - 16
E - 18

The answer apparently is 9 but I haven't any idea how that makes sense.

The only things I'm getting right are Geometry related or just simple order or operations and fractions (which I sucked at in high school).

It seems like more or less its the terminology thats throwing me off. I haven't even learned about permutations, inclusion/exclusion and combinations yet those are all over the practice I'm doing now. What is a permutation?

How would I even go about solving this -

There are 6 different ways to arrange the 3 letters E, F, and G in a row from left to right. How many more ways are there to arrange the 4 letters D, E, F, and G in a row from left to right?


/freakout

 

[Sheepo]

11
22
33
44
55
66
77
88
99


With logic problems like that last bit just draw a chart and make sure you cross out the contradictions. Then be sure to subtract six from that, because that would be a really easy mistake.

I don't remember being particularly stumped by vocabulary and I don't know any of those words either. Look at the numbers you're given and the way the question is written and see if it's possible to figure out what it wants without knowing those words.

 

[joule]

This should help..

http://www.mathsisfun.com/combinatorics/combinations-permutations.html

 

[Avoidist]

3! = 6, 4! = 24. Your answer to the second question is 24. Think of it this way:

D<permutations of EFG> + E<permutations of DFG> + F<permutations of DEG> + G<permutations of DEF> = 4*6 = 24.

 

[VirusType2]

Don't call it maths.

/freakout

 

[mindless_moder]

to make the number you need two digits
_ _

now the first digit has to be a number other than 0 because 00 is not a 2 digit integer. this leaves us with 9 possibilities for the first digit 1-9.

9 _

now the second digit must be the same as the first so theres only one possibility if we have already chosen the first digit hence

9 * 1 = 9

its the same for the second question, you have a set of 4 possible characters D E F G

_ _ _ _

to select the first character you have 4 choices D E F G

4 _ _ _

and every time you select a character you are left with one less to choose from on the next run so next time you choose from the 3 remaining chracters

4 3 _ _

and so on , it finally becomes

4 * 3 * 2 * 1 = 4! = 24

 

[Bad^Hat]

Don't call it maths.

/freakout

ALUMINIUM.

**** you Firefox, don't squiggly red line me.

 

[Xevrex]

God, I consider myself pretty good at math(s) (not to wave e-dick around because I'm always paranoid of that but) goddamn if I can't ****ing figure out some of the "number theory"/probability shit on that test. There's nothing I can't do on the SAT but I always trick myself into getting bad sleep and I don't have a proper diet, so I can kiss a 2200+ goodbye.

Especially the first question of the OP. I get it now, sure, but I always freeze up on the test. Multiply the number of possibilities, Frosted; since both digits are the same number n, we can assume only one possibility for the number. If they could be different digits, we would do 9 x 9 (9 digits, 9 possibilities for both) but since one digit is independent on the other (both are the same), there is 9 possibilities for the first and only 1 possibility for the second. So 9 x 1 = 9, A.

Factorials/combinations/permutations are shit too. 3! = 3 x 2 x 1 = 6, 4! = 4 x 3 x 2 x 1 = 24.

 

[Escaep]

Perhaps you should have started studying a little bit earlier than the night before the test.

 

[Sheepo]

I took the SAT's twice. The second time I did nothing to prepare and completely forgot about it until the day before when I glanced at the calendar. My score went up by almost 200. User results may vary.

 

[FrostedxB]

Thanks for all the help guys, I think I get this fractional function and number theory stuff now. At least my practice results are pointing in that direction.

Perhaps you should have started studying a little bit earlier than the night before the test.

Took the SAT once already, did nothing to prepare and got a 1370. This time the test is January 22, so I have a bit over a month to get ready and I do plan on kicking ass this time around.

 

[dfc05]

This is not a comment on you, but on your school -- they should have taught you permutations and combinations.

If you have the concept of the two and what the difference is, here's a time-saving hint:
Your calculator should have these 2 buttons -- nPr and nCr. Or possibly P(nr) and C(nr) with the n & r as superscript & subscript. Or if you can't find these in plain view on a graphing calculator (I don't have one on me at the moment), it's probably in the Math menu somewhere. The P button calculates a permutation for you, given n objects from which you choose r of them. The C button calculates combination.

Of course these only do you any good if you know when to use them, so if you need some examples I can pull some up. Wikipedia's write-up is extraordinarily too complex.

Alternatively -- I am sure your math teacher at school, if he/she is not a total jerk, would be more than happy to explain any and all of these to you during lunch. This would probably be far more helpful than learning by reading about it. You just need to ask.

 

[Maestro]

The ACT is a lot less frustrating than the SAT, I've taken both and the ACT science section is much more indicative of your ability to "do" science. I would take the ACT and see if you do better.

 

[Escaep]

Took the SAT once already, did nothing to prepare and got a 1370. This time the test is January 22, so I have a bit over a month to get ready and I do plan on kicking ass this time around.

For some reason I thought your post said you signed up to take it tomorrow.

The ACT is a lot less frustrating than the SAT, I've taken both and the ACT science section is much more indicative of your ability to "do" science. I would take the ACT and see if you do better.

In general, I thought the ACT was A LOT harder than the SAT.

 

[FrostedxB]

This is not a comment on you, but on your school -- they should have taught you permutations and combinations.

If you have the concept of the two and what the difference is, here's a time-saving hint:
Your calculator should have these 2 buttons -- nPr and nCr. Or possibly P(nr) and C(nr) with the n & r as superscript & subscript. Or if you can't find these in plain view on a graphing calculator (I don't have one on me at the moment), it's probably in the Math menu somewhere. The P button calculates a permutation for you, given n objects from which you choose r of them. The C button calculates combination.

Of course these only do you any good if you know when to use them, so if you need some examples I can pull some up. Wikipedia's write-up is extraordinarily too complex.

Alternatively -- I am sure your math teacher at school, if he/she is not a total jerk, would be more than happy to explain any and all of these to you during lunch. This would probably be far more helpful than learning by reading about it. You just need to ask.

My schools math department was severely lacking in the curriculum, and we learned literally the basics. Sadly I've already graduated high school a few months ago, so going to see my math teachers for help isn't quite possible. I also should go and buy a graphing calculator. :x

The ACT is a lot less frustrating than the SAT, I've taken both and the ACT science section is much more indicative of your ability to "do" science. I would take the ACT and see if you do better.

Thats what I thought, but according to my old guidance counselor, if math and science are my weak points I'm better off with the SAT. Dunno.

For some reason I thought your post said you signed up to take it tomorrow.




In general, I thought the ACT was A LOT harder than the SAT.

lol, if I signed up to take it tomorrow, I'd be quite a moron.

 

[bam23]

the problems are sometimes easier than they sound, it's the wording that gets ya.

 

[Maestro]

ACT is more based on your ability to do the required material, SAT lends itself to 'gaming the test.' I am not as good at math as I am at English/History, but I still have a pretty good grasp of science/math. I liked the ACT, it's not necessarily the same for everyone. It is still a very good idea to take both, though. You never know how you'll perform.

 

[dfc05]

My schools math department was severely lacking in the curriculum, and we learned literally the basics. Sadly I've already graduated high school a few months ago, so going to see my math teachers for help isn't quite possible. I also should go and buy a graphing calculator. :x

Ah . Well, scientific calculators tend to have it too. I can't remember if the graphing function was useful at all on the SAT. Probably not.

And the deal about "gaming" the test is true. The more practice ones you take, the better you'll do. Being a good test-taker has a lot to do with it. Sadly.